Flexible bag



FIG. 1 is a front perspective view of a design for a flexible bag showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a right side elevational view thereof;

FIG. 5 is a left side elevational view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof. 

The ornamental design for a flexible bag, as shown and described. 